Contact process and apparatus



Dec. 2z, 1970 l H. BROWN 3,549,526

CONTACT PROCESS AND APPARATUS Filed Jan. 31, 1968 7 Sheets-Sheet l Har f.5/'0 w/7 INV/vl me.

ATTOR/VEVJ Dec. 22, 1970 H. BROWN CONTACT PROCESS AND APPARATUS 7'Sheets-Sheet 2 Filed Jan. 31, 1968 mvnNN VQS .N KOM;

Nw ww @R ww s@ A fr0/@NE m Dec. 22, 1970 H. BROWN CONTACT PROCESS ANDAPPARATUS Filed Jan. 3l, 1968 7 Sheets-Sheet 3 Ha r B ro Wn INV/SNI nlDec. 22, 1970 H. BROWN 3,549,526

CONTACT PROCESS AND APPARATUS Filed Jan. 3l, 1968 '7 Sheets-Sheet 4 Dec.22, 1'970 H. BROWN CONTACT PROCESS AND APPARATUS 7 Sheets-Sheet 5 FiledJan. 3l, 1968 Dec. 22, 1970 H. BROWN CONTACT PROCESS AND APPARATUS 7Sheets-Sheet 6 Filed Jan. 251, 1968 wh MQ S MQ @w Dec. 22, 1970 H. BROWNCONTACT PROCESS AND APPARATUS 'r she'ets-sheet 7 Filed Jan. 3l, 1968 /72I lll/11111 '/l//Ill/ll lll/l A 7'7 ORA/EK) United States Patent3,549,526 CONTACT PROCESS AND APPARATUS Hart Brown, 5300 Brownway Road,Houston, Tex. 77027 Filed Jan. 31, 1968, Ser. No. 701,906 Int. Cl. B01d33/30 U.S. Cl. 210-33 23 Claims ABSTRACT OF THE DISCLOSURE Thisspecification discloses a process and apparatus for providing intimatecountercurrent contact between solid particles and a fiuid wherein suchprocess may be operated as a continuous process by utilizing two columnswith the solid particles being moved downwardly in one column andupwardly in the other column and also includes apparatus fortransferring solid particles between columns and apparatus for providingintimate contact between the solid particles and the iluids in eachcolumn. This abstract is neither intended to define the invention of theapplication which, of course, is measured by the claims, nor is itintended to be limiting as to the scope of the invention in any way.

BACKGROUND OF THE INVENTION In recent years considerable advance hasbeen made in the development of ion exchange materials in the form ofsolid particles. These particles are used to effect chemicalseparations, such as removal of undesired dissolved solids from water(water purification and softening), recovery of valuable dissolvedconstituents from a fluid (hydrometallurgy, anti-pollution, preparationof chemicals), by intimately contacting the Huid with the ion exchangeparticles. Also, important chemical processes are carried out, duringwhich fiuids are contacted by molecular sieve particles, by catalyticparticles, by other solids in particle form. Such solid particles arenormally fragile and subject to attrition. For this reason, most priorfluid-solid contacting has been accomplished in packed bed vesselsgenerally employing batch type contacting between the solid particlesand the fluid. In packed bed contactors, the fluid has a tendency tochannel through the solid particles which results in a reduction incontacting eficiency.

Prior countercurrent contacting methods have not been very satisfactorybecause of inherent leakage through the packed beds, mechanical damageto resins, expensive construction, and complex controls required.

SUMMARY The present invention relates to an improved process andapparatus for providing contact between solid particles and a fluid. Theinvention includes the continuous countercurrent contact of solidparticles with the fluid to be treated owing through one vessel and aregeneration countercurrent contact of the solid particles in a secondvessel with controlled movement of the solid particles in each vesseland between vessels. The present invention provides a Huid-solidcountercurrent contacting which assures intimate contact of the fluidwith the solid particles in each stage and prevents the solid particlesfrom bypassing any of the contacting stages, to assure a high contactingefliciency. Additionally, the present invention includes apparatus forthe controlled movement of solid particles in the contacting systemcausing very minor, if any, attrition of the solid particles.

The present invention may be used to carry out ion exchange processessuch as water treatment, purification of sugars and polyhydric alcohols,recovery and purification of biologicals, recovery and purification ofmetals,

rice

solvent purification, reagent purification, preparation of sols,catalysis, and preparation of medicines.

It is therefore an object of the present invention to provide animproved process and apparatus for contacting solid particles with afluid in a continuous system and having a high contacting eficiency.

Another object is to provide an improved process for contacting solidparticles with a fluid in which the solid particles are moved in aclosed loop and are maintained ina fluidized state during contacting.

Another object is to provide an improved process and apparatus forfluid-solid countercurrent contacting in two contacting Zones, the solidparticles in one zone being moved through said one zone in the samedirection as their settling direction in such zone and the solidparticles in the other zone being moved through said other zone in adirection opposite to their settling direction in said other zone.

A further object is to provide an improved fluid-solid contactingapparatus having a plurality of contacting stages in which substantiallyall of the solid particles are moved a single stage intermittently toprogress through a plurality of contacting stages in a directionopposite the normal ow of fiuid during contacting.

A further object is to provide an improved countercurrent uid-solidcontacting apparatus which may be shut down for any length of timewithout causing the stages of the contacting apparatus to unload thesolid particles.

Still a further object is to provide an improved apparatus forpositively moving solid particles with a minimum of fluid and withoutdamaging the solid particles.

Another object is to provide a countercurrent fluidsolid contact inwhich the solids are moved through the column in a direction oppositethe settling direction of the solid particles in the fluid.

Another object is to provide an improved continuous process andapparatus for utilizing ion exchange resins in the treatment of a fluid.

Still another object is to provide an improved continuous process fortreating water with solid particles to remove impurities therefrom.

Another object is to provide an improved fluid-solid contacting processwherein the solids are contacted by two fluids with a minimum of mixingbetween the two uids.

A further object is to provide an improved multi-stage fluid-solidcontacting process wherein the distribution of solids among the stagesis such that each stage contains substantially equal quantities ofsolids.

A still further object is to provide an improved Huidsolid contactapparatus in which the solid particles are maintained in a fluidizedcondition in a plurality of stages during contacting to preventchanneling and the solid particles are intermittently moved from onestage to the next subsequent stage in a direction opposite to thedirection of fluid ow during contact whereby countercurrent fluid-solidcontact is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a generalized schematic tlowdiagram of the improved process of the present invention.

FIG. 2A is a schematic view of an apparatus of the present inventionused to soften hard water. FIGS. 2B, 2C, 2D, and 2E are schematic viewsimilar to FIG. 2A which respectively illustrate the ow of resins, thetlow of hard water, the flow of soft water and the flow of brine in theapparatus shown in FIG. 2A. FIG. 2F is a schematic view of the apparatusshowing the displacement device for moving the solid particles throughthe column.

FIG. 3A is a schematic view of a simple contact apparatus illustratingthe fluidized condition of the solid particles during contact. FIG. 3Bis a similar view illustrating the periodic movement of the solidparticles to the next lower tray to show the possibility of some solidparticles bypassing a contacting stage or tray during such movement.FIG. 3C is a schematic view of a similar contacting structureillustrating the function of the delay bafes to prevent solid particlesfrom bypassing a contacting stage or tray. FIG. 3D is a schematic viewof a similar contacting apparatus having means to regulate the quantityof solids which remain in each stage during contacting upfiow by fluid.

FIG. 4A is a cross sectional view of a contacting structure illustratingthe fiuidized condition during contact. FIG. 4B is a view of the samestructure but illustrating the movement of the solid particles to thenext higher contacting stage which movement is in a direction oppositeto the normal settling direction of the solid particles in the fiuid.

FIG. 5A is a cross-sectional view of a solid particle transfer orpumping device. FIGS. 5B, 5C, 5D, and 5E illustrate respectively theintake of solid particles and fluid through the inlet port, the passageof the solid particles and liuid past the inlet valve into thedisplacement chamber, the seating of the inlet valve and the opening ofthe outlet valve and the discharge of the solid particles and fiuidthrough the outlet port. FIG. 5F is a sectional view taken along lineSF-SF in FIG. 5A to illustrate the inlet Valve. FIG. 5G is a sectionalview taken along line SG-SG in FIG. 5A to illustrate the configurationof the central chamber of the apparatus.

FIG. 6 is a cross-sectional view of a preferred form of a solid particletransfer or pumping device.

FIG. 7A is a plan view of a modified form of contacting apparatus inwhich the solid particles are moved from stage to stage in the directionof settling. FIG. 7B is a sectional view of this contacting apparatustaken along line 7B-7B in FIG. 7A. FIG. 7C is a plan view of a modiedform of contacting apparatus. FIG. 7D is a cross-sectional view of thisapparatus taken along line 7D-7D in FIG. 7C. FIGS. 7E and 7F arecross-sectional views of the preferred form of contacting apparatussimilar to the apparatus shown in FIGS. 7C and 7D.

FIGS. 8A, 8B, and 8C are sectional views of the contacting apparatusshown in FIG. 7E to illustrate respectively the liuidized state of solidparticles during full fiow rate contacting, the fluidized state of thesolid particles at reduced fiow rate through the apparatus, and theposition of the solid particles in the apparatus at zero fiuid flowrate.

FIG. 9A is a plan view of the preferred contacting apparatus used formovement of the solid particles in their settling direction. FIG. 9B isa sectional view of this apparatus taken along line 9B-9B in FIG. 9A.FIG. 9C is a sectional view of this apparatus taken along line 9C-9C inFIG. 9B to illustrate the configuration of the passages communicatingbetween the contacting areas and the space below the apparatus.

FIG. 10A is a plan view of the preferred form of contacting apparatusused for movement of the solid particles in a direction opposite totheir settling direction. FIG. 10B is a sectional view of this apparatustaken along line 10B-10B in FIG. 10A.

FIG. 11A is a schematic view of an apparatus suitable for use inrecovering uranium product from an enriched uranium slurry andillustrates the fiow path of resins through the apparatus. FIGS. 11B and11C are similar views of the same apparatus and illustrate the flow pathof wash water (FIG. llB) and the ow paths of the slurry and strippingsolutions (FIG. 11C).

DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of the presentinvention provides intimate contact between a first fiuid and solidparticles which are retained in a closed loop, with the liow velocity ofthe first fiuid being controlled to maintain the solid particles in auidized state to assure intimate and complete contact, while notallowing the resins to be `carried out of the loop by the flow of theliuid. This process provides a closed loop circuit in which the solidparticles are moved to provide a countercurrent fiuid-solid contact. Inthe first portion of the circuit, the solid particles are intimatelycontacted by the first fiuid. In such contact, the solid particlesperform a specific function, such as, ion exchange, preferentialadsorption, catalyst, etc. In the second portion of the circuit, thesolid particles are intimately contacted by a second fiuid, which fluidperforms the specific function of regenerating the resins to a conditionwhereby they may again perform their function in the first portion ofthe circuit. When desirable, the above can be accomplished withoutcausing any mixing of the first and second fluids.

The movement of the solid particles through the circuit is such that acountercurrent contact is provided in both portions of the circuit,i.e., the most active solid particles are intimately contacted by theweakest fluid in the system immediately prior to the discharge of thefluid from the system. This countercurrent contacting is repeated atsuccessive points along the closed loop path followed by the particles.Such movement of the solid particles through the circuit is accomplishedwithout requiring the use of separate mechanical elevating devices, forexample, pumps. This is accomplished by providing for the movement ofthe solid particles in the first contacting portion in a directionopposite to the direction of flow of the fluid but in the normalsettling direction in such fluid, and providing for the movement of thesolid particles in the second contacting portion in a direction alsoopposite to the direction of flow of the fiuid but in a directionopposite to their normal settling direction in such fiuid.

This process is diagrammatically shown in a Very general form in FIG. l.The solid particles are delivered to the first exchange chamber and areintimately and countercurrently contacted therein by the first exchangefiuid. In this first exchange chamber, the solids perform theirpreselected function with respect to the first exchange fiuid. Theparticles are delivered from the first exchange chamber to the firstwash chamber by the No. 1 control means. In the first wash chamber, theparticles are intimately and countercurrently contacted by the firstwash fluid. From the first wash chamber, the particles are delivered tothe reservoir by the No. 2 control means. From the reservoir, theparticles are delivered to the second exchange chamber by the No. 3control means. The second exchange fluid is brought into intimatecountercurrent contact with the particles in the second exchangechamber. The particles after being delivered by the No. 4 control meansto the second wash chamber are intimately and countercurrently contactedtherein by the second wash liuid. The No. 5 control means delivers theparticles from the second wash chamber to the first exchange chamber.

In FIG. l, for many applications the functions of two or more controlmeans may be combined into a single control means. In certainapplications some wash charnbers are not required. In other applicationsa third exchange chamber with accompanying wash chamber and controlmeans may be added. For example, when used to soften water, the firstwash chamber, the No. 2 control means, and the No. 4 control means arenot required.

Assuming that the particles used in this process settle downwardly inthe fluids used, and the circuit as shown has two vertical legs, one legin which the particles are moved downwardly and the other leg in whichthe particles are moved upwardly as hereinafter described, thefiuid-solid particle contact is countercurrent and the particles aremaintained in a fluidized state during such contact. For convenience ofthe subsequent discussion herein, a column in which the particles aremoved in their normal settling direction is referred to as a type Acolumn and the column in which the particles are moved in a directionopposite their normal settling direction is referred to as a type Bcolumn. It is assumed for purposes of discussion that the particles aremore dense than the fluid and therefore normally settle downwardly.

The control means used to transport the solid particles between chambersmoves such particles with a minimum of uid accompanying them and alsominimizes solid particle attrition.

WATER SOFTENING PROCESS The application of this process to watersoftening is shown in FIGS. 2A through 2E. The apparatus illustratedschematically includes the exhaustion column (type A) and theregeneration column 12 (type B). Hard water containing for examplemagnesium sulfate, is delivered through inlet 14 into the lower end ofcolumn 10 and flows upwardly therein through a plurality of stagesproviding intimate contact with resin particles as shown in FIG. 2C. Theresin particles contemplated for such water softening would be a typewhich exchange sodium ions for magnesium ions. When delivered to column10 such particles normally would be in the sodium form. Such resinparticles, when brought into intimate contact with the hard water,exchange their sodium ions for the magnesium ions in the water, therebyconverting the magnesium sulfate to sodium sulfate to soften the waterand the particle exchange sites are converted to the magnesium form.Such resin particles can then be regenerated by contact with a brine(sodium chloride solution) whereby the particle exchange sites areconverted to the sodium form and the magnesium ions form magnesiumchloride in solution which is discharged from column 12 as waste throughoutlet 16 under control of metering pump 18. The soft water isdischarged from column 10 through the upper outlet 20.

Resin particles are delivered from column 12 through duct 22 into theupper end of column 10. Since the liow of hard water into the column 10preferably remains substantially constant, the resin control means 24 isoperated to provide an intermittent flow of water downwardly in column10 whereby the resin particles are moved downwardly one stage or tray ata time. Thus, with the water flowing normally upwardly through column10, it is initially contacted by the resin particles already nearlydepleted of sodium ions and as it nears the top of column 10, it iscontacted by resin particles having essentially all of their exchangesites in the sodium form, thereby providing a countercurrent type ofintimate contact between the water and resin particles.

The resin control means 24 may be any means which will create acontrolled short duration downflow of iluid in the entire columnarassembly of contacting stages between water inlet 14 and resin inlet 22,A simple form of such displacement device shown in FIG. 2F employs apiston 21 movable in a cylinder installed at 24 in the column 10,wherein the piston 21 may be driven by the cam follower 33 responsive tocam 25 so that the piston 21 slowly entering the cylinder slowlydisplaces fluid up the column 10 over an extended time period, thenresponding to cam action the piston 21 quickly withdraws in the cylindercreating a sudden downward movement, or pulse, of the entire colu-mn ofliquid in column 10 above means 24. To use this control means thesurface of liquid just above the outlet is usually held at atmosphericpressure. In the event the column must be sealed from contact with theatmosphere, or that the column must be operated at elevated pressure, asecond piston 21 and cylinder of same displacement may be installed incolumn 10 at the same elevation or above inlet 22. Such second piston 21is suitably linked by crank 27', link 29 and crank 27 to the firstpiston 21 so that the two pistons move simultaneously so as to createequal and opposite volume displacements in the column 10. This simplemeans has one shortcoming, namely that the sudden downward pulse startswhile the resin particles in each stage compartment are highly fluidizedby the upilowing contacting fluid. Thus to transfer substantially allparticles out of one stage cornpartment into the one next below mayrequire a downow of a total volume several times greater than isrequired when the resins are settled and at rest at the beginning of thedownward pulse. The greater the total volume pulsed down, the greatermust be the height of each stage-compartment to assure minimum mixing ofparticles in adjoining compartments during the pulsing operation. Ittherefore is desirable to minimize the total volume pulsed downwardly inthe column. Also it is difficult to transfer duplicate volumes of resinsdownwardly at each pulse if the fluid upfiow rate is different duringdifferent pulse occurrences. One Way to overcome this problem is toallow the resin particles to settle onto the perforate platesimmediately prior to starting the downward pulse. This may beaccomplished by use of a cam design which moves the piston outwardly ata rate sufficient only to compensate for the incoming hard water justlong enough for the resins to settle, then produce the transfer ofparticles by downflow through the stages. A preferred method uses thefollowing procedure: (l) stop the hard water inflow at 14, (2) delay oneor two seconds to allow the resin particles to settle, (3) actuate thedisplacement means creating the sudden down pulse of a preselectedvolume to transfer predetermined volume of resins, and (4) resume inflowof hard water after waiting a short interval allowing resin particles tosettle sufficiently so that resumption of upflow does not return lostparticles upwardly through the next higher tray.

The resin particles from the reservoir 26 in column 10 are delivered tothe lower end of column '12 by the resin transfer means 28 as shown inFIG. 2B. Such resin transfer means 28 not only delivers the resinparticles to column 12 with a minimum of water from column 10, but mayalso be designed to provide an intermittent reversal of the ow thereinto cause the resin particles to progress upwardly therein one stage ortray at a time.

When used for water softening, the preferred form of the resin transfermeans 28 is substantially a cyclic positive displacement metering pumpwhich periodically removes a preselected volume of a slurry consistingof water and resin particles from the reservoir 26, and periodicallydelivers same to the base of the regeneration column 12. In addition topositively moving the metered volume of resins and water from the baseof column 10 into the base of 12, the resin transfer device 28 reventsany other movement of water or resins between the tWo columns. Thisblockage assist the proper functioning of the resin control means 24.

The cycling of resins downward through column 10 is substantiallyindependent of the cycling of resins up through column 12 in that resinsare periodically moved down in colurrm 10 at intervals only sufficientlyfrequent that the resins become properly loaded with hardness by thetime they reach the base of column 10. Such cycling may be controlled bya sequencing timer or by a water meter when the hardness of the enteringwater is relatively constant. When the hardness varies from time totime, the cycling time may be controlled by a hardness sensor placedseveral trays below the top tray in column '10. Thus the rate at whichresins enter the reservoir 26 depends upon the total quantity ofhardness removed per unit time from the water being treated.

The cycling frequency for column 12 may conveniently be set at themaximum which allows the resins to be regenerated properly as theyascend through column 12. A photocell inserted in the lower part ofreservoir 26 (together with a suitable light source) can sense whenresins cover the photocell. When the photocell is covered, its signalcan be used to keep the column 12 cycling continuously, and thustransporting resins upward through column 12 and into the top of column10` at the maximum capacity of the regeneration column 12. When suchcontinuous periodic removal of resins from reservoir 26 uncovers thephotocell, its signal stops the cycling of the regeneration column 12until column 10, by its independent action, rells the reservoir 26. Thiscontrol arrangement therefore automatically governs the systemoperation.

Brine is delivered by metering pump 30 through inlet 32 to anintermediate position in column 12. As shown in FIG. 2E, some of thebrine may move upwardly in column above inlet 32 into the washingsection but the downward flow of the wash water is controlled to washthe brine from the resin particles and to prevent the brine fromreaching the top of column 12. The brine flows downwardly through theplurality of contact stages in column 12 in intimate contact with theresin particles at each stage and exchanges the sodium ions from thebrine for the magnesium ions on the resin particle exchange sites. Asmentioned, the spent brine is discharged from the lower end of column 12through outlet 16 under control of metering pump 18. The resin particlesreaching the top of column 12 are carried through duct 22 into column10. The soft wash water for the upper end of column 12 is providedthrough duct 22` from the upper end of column 10 as shown in FIG. 2D.The volume of brine injected into column `12 is determined by the volumeof resin particles that move up through column 12 so as to assure thatthere are sufficient sodium ions available to adequately regenerate theresin particles. The discharge from column 12 is controlled by meteringpump 18 and is somewhat greater in volume than the brine injected plusthe hard water carried over with the resin particles from column 10 soas to assure an adequate flow of wash water into the top of column 12.Thus, the flow of wash water not only serves to wash the regeneratedresins free from brine but also serves to dilute the brine to thedesired concentration. it il Thus, in this water softening process, thehard water is softened in the column 10 by ion exchange with the resinparticles which are positively moved downwardly in column 10 and thebrine regenerates the resin particles which are positively movedupwardly in column 12 as shown in FIG. 2B. The resin control means 24and the resin transfer means 28 are controlled to move the resinparticles in the closed loop at a rate to assure the desired softeningof the water and the most ecient use of the sodium ions in regeneratingthe resin particles.

SOLID PARTICLE ACTION-TYPE A COLUMN The process of the presentinvention, as previously described, maintains the solid particles in afluidized condition during periods of contact. FIG. 3A illustrates asimple type A column 34 having perforated trays 36 extendingtransversely across the interior of the column 34. As indicated by thearrows, the fluid within the column 34 flows upwardly, passing throughthe perforations in each tray 36, and is in intimate Contact with thesolid particles between the trays. The size of the perforations arepredetermined to provide sufficient uid velocity therethrough to preventthe solid particles from dropping through the perforations during upwardfluid flow and to fluidize the solid particles above the tray to avoidchanneling of the uid through the particles. The rate of fluid flowbetween trays should be less than, but almost equal to, the rate ofsettling of a specified size of solid particles in the fluid so thatparticles are not carried by the flow to the next higher tray whilemaintaining nearly maximum expansion and fluidization of the particlesbetween trays.

In this perforate tray type A column, control of the fluid velocities isaccomplished by preselecting the ratio of flow area through theperforations in the trays to the flow area of the column between thetrays and controlling the rate of fluid introduced into the column. Itis generally preferred that the ow area through the tray perforations bebetween ten to twenty percent of the How area of the column betweentrays. Also, the individual perforations are preferred to have adiameter from three to six times the diameter of the largest solidparticle to be used to assure that the particles do not bridge over aperforation when the particles are being transported downwardly in thecolumn.

The solid particles are intermittently moved downwardly from one tray tothe next lower tray. This movement of the solid particles isaccomplished by reversing the uid ow to cause all of the uid to flowdownwardly within column 34 a distance that is sufficient to carry theresins from the contacting compartment 35 through the tray 36 and intothe contacting compartment 35 next below. It is generally preferred tostop the upward fluid flow for a short period of time before reversingthe flow. This period of no ow allows the particles to settle downwardtoward the tray to thereby minimize the volume of flow reversal neededto transfer the particles. The effect of such flow reversal on the solidparticles within column 34 is shown in FIG. 3B. The solid particles arecarried downwardly through the perforations in trays 36 and when the uidflow returns to the upward direction, the particles which have beenmoved are fluidized `on the next lower tray as shown in FIG. 3A.

FIG. 3B illustrates some problems commonly encountered in the use of theperforated trays 36. Some of the particles on the tray are not carrieddown to the next lower tray when the uid flow reverses. In the preferredprocess of the present invention, it is desired that all solid particlesbe moved to the next lower tray which would assure a uniformity ofcondition of all of the solid particles on each tray. The holdover ofparticles on a tray can be minimized by proper location, quantity andsize of the perforations in trays 36. Also, in the transport or movementof the particles to the next lower tray, the first particles to passthrough the perforations may reach the next lower tray and pass throughits perforations before the flow reversal is completed. This bypassingof residence in a contacting stage or tray by the particles isundesirable.

The aforementioned particle bypassing may be minimized by modifying thecolumn as shown in FIG. 3C. The modifiied column 38 includes thetransverse perforate trays 40 and also includes a means for delaying thepassage of solid particles downwardly through the space between trays 40after they have passed through the tray perforations responsive to flowreversal. Such delay means, as illustrated, takes the form of perforateplates or baffles 42 positioned below each tray 40. This delay means hasbeen found to be effective to prevent particles from bypassing residencein a contacting stage. Perforate plates 42 are preferred to have a largeratio of perforate area to solid area, compared to the ratio used for aworking tray 40.

Continuous operation of a column comprised of a vertical assembly ofperforate plate trays sometimes results in the collection of a largeexcess of particles on one tray accompanied by a severe shortage ofparticles on another tray in the same assembly. This indicates a needfor a means to regulate the normal particle thickness on each tray. Sucha regulating means is shown in FIG. 3D. A chimney 43 is installed onabout live percent of the perforate holes. The interior diameter of thechimney is the same as that of the perforation in the plate. The chimneyregulates the particle bed thickness to be substantially equal to thechimney height by conducting particles through the chimney only when thebed thickness execeed the chimney height.

While a type A column having only perforate trays for providing thedesired plurality of stages of intimate fluid-solid contact may be usedsuccessfully, they are subject to the disadvantage that they allow amajor portion of the particles to settle through the trays to the bottomof the column when the fluid flow is stopped for an extended period oftime. This solid particle unloading necessitates a start-up period ofoperation when the fluid flow is thereafter resumed to redistribute thesolid particles properly on each of the contacting trays beforeeflicient countercurrent contact may again be established. During suchstart-up period, the process is not effective to perform its desiredfunction. This unloading of the column during shutdown may be readilyovercome by proper design of the contacting apparatus as hereinafterexplained. It is recognized, however, that this disadvantage may not bea -sufllcient factor to require the adoption of a more complexcontacting apparatus, particularly where the process is intended tooperate continuously. It is, however, a major factor in applicationswhere the process is intended to operate on an intermittent basis.

A practical application of the type A column using the perforate platesas illustrated in FIGS. 3A, 3B, 3C, and 3D is one in which it isanticipated that the flow of fluid up through the column will not bediscontinued, which would cause particles to fall to the bottom of thecolumn. However, shutdown periods will occasionally occur for servicingof some of the external components. or because of loss of the externalfluid supply, power failures, etc. A start-up period would then benecessary in order to return the column to a status of efficientoperation. A practical solution to such contingencies would be toprovide auxiliary means to maintain a very low flow rate just suflcientto prevent particles falling through perforations. Such minimal flow ofthe regular contacting fluid could often extend the interval long enoughbetween necessary particle transfer pulses to permit required servicingof external controls. When a longer interval is required, auxiliarypumping means may be used to circulate fluid from the outlet of thecolumn back to the inlet, a practice which usually would not upset thechemical balance of the column.

SOLID PARTICLE ACTION-TYPE B COLUMN As previously explained, a type Bcolumn provides an intimate countercurrent contact between a fluid andsolid particles in which the solid particles are moved through thecolumn in a direction opposite to their settling direction in the fluid.As in the type A column, it is preferred that the fluid-solid contactoccur with the solid particles in a fiuidized state resulting from theflow of fluid through the particles.

The contacting apparatus shown in FIGS. 4A and 4B provides theaforementioned fluid-solid contact and the progressive upward movementof solid particles in a fluid in which they normally settle downwardly.The column 44 includes a plurality of cups 46. Each of the cups 46 isformed to have an upwardly extending tubular projection 48 and a lowertubular projection 50, offset to one side of the cup and defining thepassage 52 cornmunicating through the cup. The cups 4K6 are assembled asshown with the projections 48 and 50 positioned to the opposite sides ofthe column 44 from the projections of the adjacent cups. Suitablesealing means, such as, O-rings 54, are provided between cups as shown,to make the column fluid-tight.

The normal contacting flow of fluid through column 44 is downwardly asshown in FIG. 4A. The fluid flows downward through the passage 52 intothe bowl 56 of the next lower cup 46. The solid particles collect in thebowl 56, which is sloped downwardly towar-d the position immediatelyunder passage 52. As the fluid flows upwardly within the bowl 56, itfluidizes the solid particles and intimately contacts them. To preventparticle carryover to the next passage, the size of cups and the rate offluid flow should be preselected so that the fluid flow velocity in theupper portion of the bowl is le-ss than the settling rate of the solidparticles in the fluid. The fluid exits from the bowl 56 into thepassage 52 and similarly flows through each succeeding lower cup orcontacting stage.

When the solid particles have remained in the contacting stage for adesired period of time, the fluid flow is reversed to cause the solidparticles to be moved to the next higher cup 46. This action is shown inFIG. 4B. Before reversing the fluid flow, such flow is preferred to bestopped thereby allowing the particles to collect in the lower portionof the bowl 56 to minimize the volume of reverse fluid flow required tomove the particles. In the reverse flow, the fluid passes upwardlythrough the passage 52, flows downwardly in the bowl 56 and carries thesolid particles up the passage 52 into the next higher bowl 56. Thisflow reversal is a controlled volume of flow and is preferred to be justenough volume to transport the solids in each stage or cup to the nexthigher stage or cup. In this manner, a countercurrent contacting isestablished in the column 44 with the fluid normally flowing downwardlyand the solid particles being transported upwardly through the columnone stage at a time. Thus, intimate countercurrent contact isestablished between the solid particles and the fluid and the movementof the solid particles progresses upwardly through the column in adirection opposite to their settling direction in the fluid. The designand use of the type B column allows a complete closed loop circuit to beestablished which eliminates the need for any specific elevating device,other than the type B column, to return the particles to the top of thetype A column.

While the foregoing discussion has assumed that the settling directionof the solid particles in the fluid is downward, the process andapparatus of the present invention is equally applicable to thecontacting of solid particles which normally rise when submerged in thefluid. It is suggested, however, that such normally rising solidparticles may be used by inverting both of the columns so that in thetype A column, the solid particles travel upwardly therethrough and inthe type B column, the solid particles are moved downwardly, therebyproviding the closed loop circuit for the movement of the solidparticles.

In discussing the process and apparatus of the present invention,reference is made to the contacting of solid particles with a fluid. Itis believed that the present process is applicable to gases, liquids andliquid slurries. The inclusion of gas in a column, as hereinafterdescribed, may dampen the reverse flow pulse in remote portions of thecolumn from the pulse source sufficiently so that the transport of solidparticles may be adversely affected. This is particularly true in thetype B column. Another problem which should be considered in theoperation of the columns in a gaseous system results from the presenceof small amounts of moisture which causes the solid particles to adhereto the column structure and to each other. Further, such moisture maycoat the solid particles and thereby prevent intimate contact betweenthe gas and the solid particles. Therefore, as used herein, the termfluid is intended to include liquids, liquid slurries and only thosegases and combined liquids and vapors which have the characteristicsenabling them to fluidize the solid particles during contacting flowan'd to transport the particles, as described, responsive to reverseflow pulses.

SOLID PARTICLE CONTROL MEANS- METERING PUMP As previously explained, itis desirable to transfer the solid particles from one column to theother column with a minimum of fluid carry-over while preventing damageto the solid particles and backflow of fluid through the control means.Also, the transfer means, such as the particle transfer means 28 in thewater softening system of FIG. 2A should be capable of being controlledso that it periodically transfers a predetermined amount of solidparticles and volume of fluid from one column to the other. FIGS. 5Athrough 5G illustrate the structure and operation of a transfer means,hereinafter referred to as a particle transfer means or metering pump58.

The pump 58 includes a body 60, the cover 62 and the diaphragm 64. Thebody 60 defines the inlet port 66 which communicates with the inletchamber 68 defined in the body 60 above the inlet valve seat 70. Thebody 60 also denes the displacement chamber 72 above the outlet valveseat 74 and the outlet chamber 76 which is in communication with theoutlet port 78. The diaphragm 64 is secured to the cover 62 by suitablemeans such as strips 80. The diaphragm 64 consists of three workingportions. The inlet valve portion 82 of diaphragm 64 is adapted to bemoved responsive to pressures in the upper valve chamber 84 in cover 62into and from engagement with the inlet valve seat 70. The pumping orcentral portion 86 of diaphragm 64 is adapted to be moved responsive topressures in the pump chamber 88 into the displacement chamber 72 tocontrol the volume of uid and particles therein. The outlet valveportion 90 of diaphragm 64 is adapted to be moved into and fromengagement with outlet valve seat 74 responsive to pressure in lowervalve chamber 92. As shown, the body 60 denes ribs 94 which project intothe central displacement chamber 72 to limit the movement of the centralportion 86 of diaphragm 64 into the displacement chamber 72. The valveseats 70 and 74 are both contoured as shown in FIG. F to assuretight-seating engagement of the respective diaphragm portions thereon.

The sequence of operation comprising one complete operating cycle ofpump 58 is illustrated in FIGS. 5B through 5E. In FIG. 5B, the inletvalve 82 is open and fluid and solid particles are being drawn into thedisplacement chamber 72 by the movement toward the right of diaphragm86. FIG. 5C represents the period after the intake during which alldiaphragms are stationary while the solid particles are allowed tosettle in the displacement chamber 72. The arrow shows upward ow of uiddisplaced by particles falling through the inlet valve. FIG. 5D showsthe inlet valve closing and the arrow shows upward ow of Huid displacedby the closing motion of the inlet valve diaphragm 82. This upward flowwashes any remaining particles from the inlet valve seat 70 as the valvecloses. In FIG. 5E most of the fluid and solid particles have been movedout through the open outlet valve by the leftward movement of diaphragm88. The straggling particles remaining in the displacement chamber aresettling through the open outlet valve. Simultaneously a volume of uidequalling the particle volume is displaced and moves upward through theoutlet valve, as indicated by the arrow.

The movement of particles and fluid through this device is controlledsolely by the action of the three diaphragm segments. Since the movementof each diaphragm segment is separately controlled, the sequence ofevents illustrated by FIGS. 5B through 5E represents one manner of usingthe device. Obviously, this sequence may be varied as conditionsdictate; for example, in one application, it has been found convenientto employ a sequence in which the inlet valve closes simultaneously withthe opening of the outlet valve, and later in the cycle the inlet valveopens simultaneously with the closing of the outlet valve. Despite thisdeparture from ideal operating theory, it was found that the rapid fluidmovement occasioned by quickly closing the valves, successfully washedall particles off of the valve seats. In other applications, a continuedsmall movement of the displacement chamber diaphragm 88, concurrentlywith the closing of either valve may be used to create an upward tiow ofuid, out of which the particles previously have settled, across theoutlet valve seat or the inlet valve seat, as requirements dictate, inorder to completely wash those seats clean of particles as therespective valves close.

The preferred form of uid transport device or metering pump 96 is shownin FIG. 6. The pump 96 employs a set of cylindrical diaphragms in placeof the at diaphragm illustrated in FIGS. 5A through 5G. This pump 96provides valves which open fully to increase the throughput capacity perunit length of valve seat, and has a structure enabling convenientservicing of the device. In this design a horizontal cross-section iscylindrical thereby providing economy of manufacture. This preferredform as shown in FIG. 6 includes an upper inlet valve, a lower outletvalve, and a central displacement chamber therebetween having means forcontrolling and changing the volume of the central displacement chamber.The body 9S of pump 96 denes the inlet 100, the inlet valve seat 102,the outlet valve seat 104 and the outlet port 106. Seats 102 and 104 areboth annular and extend inwardly into the space defined by the body 98.Body 9S defines the cylinder 108 in which piston 110 is positioned toprovide the volume changing means. The core 112 is positioned centrallywithin body 98 as shown and is provided with suitable means (not shown)to secure it in such position. Tubular diaphragm 114 is positioned insurrounding relation to core 112 and is secured by the three bands 116,118-, and 120 to core 112. The diaphragm 114 may be divided into twoseparate units, each being secured by two bands. The core 112 denesupper annular groove 122 and lower annular groove 124. As shown,diaphragm 114 extends across the grooves 122 and 124 and is free toexpand outwardly responsive to pressure within the respective grooves.The upper groove 122 is positioned radially inward of inlet valve seat102, so that when the portion of diaphragm 114 covering groove 122expands outwardly, it engages valve seat 102. Also, groove 124 isradially inward of outlet valve seat 104 so that when the portion ofdiaphragm 114 covering groove 124 expands outwardly, it engages valveseat 104. Passage 126 communicates with groove 122 and passage 128communicates with groove 124 so that the portions of the diaphragm 114covering the grooves may be independently expanded and contracted intoand from seating engagement with their respective valve seats to therebyfunction as inlet and outlet valves.

The sequence of operation of metering pump 96 is substantially the samedescribed in relation to metering pump 58. The inlet and outlet valvesare actuated by pressures applied through passage 126 to groove 122 andthrough passage 128 to groove 124, respectively. Application of suchpressure expands the portions of the tubular diaphragm 114 causing it tocontact the respective valve seats creating the desired valve closure.Piston in cylinder 108 represents means to vary, in a controlled manner,the volume of the displacement chamber 130. If desired, diaphragm meansor other displacement means may be substituted for the piston andcylinder illustrated.

The relative action and reactions between the movement of inlet valve,displacement chamber volume changes, movement of outlet valve, particlesettling, ushing of valve seat immediately prior to valve closure, allduplicate those described regarding operation of metering pump S8. Themajor advantage of metering pump 96 over that of metering pump 58 isthat it may be constructed easily in sizes capable of handlingrelatively larger volumes, and its valve design does not have cornerswhich may trap particles.

Slight changes in the sequence of operations of the valves and ofdisplacement piston 110 permit this particle transport device ormetering pump to perform its functions with the same cxibility exhibitedby metering pump 58.

When either pump 58 or pump 96 is operated at reasonable capacity ofparticle throughput, and when sufficient time is allowed for particlesto settle as described hereinabove, valves do not close on resinparticles. However, as the throughput of particles is increased, and thecapacity of the device is taxed, particles occassionally are trappedbetween the valve seat and the diaphragm by the closing of a valve. Useof a soft natural or synthetic rubber material for diaphragm 114 permitsoperating of the device at these higher capacities where occasionalparticles are trapped, with only minimal, if any, damage to particleseven though they are quite fragile.

The primary use of the metering pumps 58 and 96 described heretofore hasbeen to function as a resin transfer device between two columns. Thepumps also may perform a dual role. In addition to transfering a meteredvolume of particles out of type A column into type B column, the pumpsometimes also serves as the control means which moves the particlesthrough the type B column, such as column 12 in FIG. 2A.

Thus, the particle transfer devices or metering pumps provide the meansfor controlled transfer of solid particles between columns in which theamount of uid transferred with the solid particles is controlled anddamage to fragile solid particles is minimized. The particular particletransfer devices described may also be used to pump a metered volume ofliquid which volume may be varied to preselected amounts within sizelimits of the devices simply by controlling the actuation of thedisplacement means. These particle transfer devices have been describedwith reference to solid particles which have a density greater than thedensity of the fluid accomp-anying them. These same devices are suitablefor transferring fluids with solid particles which have a density lessthan the fluid; however, in such use the devices are inverted toposition the inlet valve below the outlet valve so that particlessettling upward move toward the outlet.

It is further contemplated that by providing a positioning of the inletvalve, the displacement chamber and the outlet valve so that solidparticles tend to settle toward and through the outlet valve allcombinations of fluids and solid particles may be transferred by thetransfer means of the present invention. For example, in pumping liquidand solid particles wherein the solid particles are less dense than theliquid and settle therein in an upward direction, the 'pumping devicesshould be inverted from. the position shown and described so that theoutlet is above the inlet and to thereby allow solid particles to settletoward the outlet.

CONTACT ING STRUCTURES FOR TYPE A COLUMN FIGS. 7A through 7F disclosecontacting structures which are intended for use in providing huid-solidcontact in a type A column, that is, a column in which the solids areprogressively transported through the column in the direction in whichthey settle in the fluid. Each of these structures is designed to directthe upflowing uid through the solid particles to cause the particles tobe in a uidized state during contacting. Each struc ture is alsointended to move substantially all of the solid particles only one stage(to the next lower structure) with each reverse ow pulse imparted to theuid in the column. Also, these structures prevent unloading of thecolumn (the settling of solid particles through the trays to the bottomof the column) when the fluid upow through the column is discontinuedfor an extended time.

FIGS. 7A and 7B illustrate one form of contacting structure or tray 132.The tray 132 is shown to` be formed of a suitable plastic, such as,polypropylene and dencs a plurality of contacting lbowls 134. As shown,tray 132 is square in shape and the bowls 134 are defined by a pluralityof upstanding ridges 136 extending across the upper surface of tray 132.The ridges 136 have a pointed upper surface and sides which slopedownwardly and inwardly toward the center of each bowl. The tray 132also includes the upstanding walls 138 which function to define thesides of the outer bowls and to provide adequate spacing for an assemblyof a plurality of the trays 132 into a contacting column. The tubes 140extend through the tray 132 and each connects to four depending tubes142. Each of tubes 142 open downwardly immediately above the center ofone of the bowls 134. Thus, a communication is provided from the spacebelow the tray 132 to the central portion of each of the contactingbowls 134.

In operation, contacting Huid ows upwardly through the tubes and isdistributed through the tubes 142 downwardly into the bowls 134. Thesolid particles on the tray 132 are uidized within each bowl 134 toprovide an intimate contact with the uid. When it is desired to move thesolid particles downwardly to the next tray in the column, the upowingfluid is stopped and reversed. The solid particles are picked up in eachbowl by the reverse fluid flow and conducted through tubes 142 and 140and are discharged into the space below tray 132. Merging the fourpassageways 142 into the single passageway 140 is for convenience ofconstruction only. If desired, each of the passageways 142 could beconnected through the tray 132 into the compartment next below.

The structure of tray 132 clearly prevents solid particle unloadingduring shutdown. Also, the central positioning of the open end of tubes142 in each of the bowls and the sloping sides of the bowls 134 assuresthat substantially all of the solid particles are moved to the nextlower tray with each reverse flow pulse. Particle bypassing of trays inthis type column may be excessive for the reasons portrayed in FIG. 3.However, such bypassing may be reduced by various means, for example,bales shown in FIG. 3C or horizontal passageways shown 'in FIGS. 7C and7D.

The tray 132 may be constructed as shown having sixteen of the bowls 134or any other suitable multiple of four which provides sufcient solidparticle and fluid flow capacity.

The structure of tray 144 shown in FIGS. 7C and 7D is another form ofstructure which may be used for a type A column. The tray 144 is shownto be formed of a plastic material because of the ease with which suchmaterial may be formed to produce the desired shape and chemicalinertness. The tray 144 includes the walls 146 extending upwardly aroundthe exterior thereof and a plurality of ridges 148 extending upwardly todefine a plurality of contacting bowls 150. Each of these bowls 150 isgenreally cup-shaped. The tray 144 defines the passages 152. Each of thepassages 1'52 extends downwardly from the central portion of its bowl150 and turns to a horizontal direction terminating in communicationwith the space below the tray 144. The direction in which the horizontalportion of the passage 152 extends from the vertical portion is bestshown in FIG. 7C. It is generally preferred that such passages 152 beoriented with respect to each other to provide a circular ow of fluidand solid particles below each tray during the transport of the solidparticles to the next lower tray. This motion assists in maintaining thesolid particles above the next lower tray until the reverse pulse iscompleted. The underside of the tray 144 is substantially flat to allowa plurality of the trays 144 to be assembled into a contacting column.In such assembly, the upper edge of the'walls I146 of one tray areadapted to seal against the lower surface of the next higher tray.

In operation, upilow of fluid through tray 144 proceeds through thepassages y1'52 into the central portion of each of the contacting bowls150. The upwardly owing fluid passes through the solid particles whichtend to settle into the cups, causing them to be fluidized and therebyassures that each particle is available for intimate contact with thefluid. The fluid flow rate is controlled in conjunction with the flowarea of the passages 152 and the flow area above the bowls 150 to assurethat during contacting, the solid particles remain in their respectivecompartments, i.e., the particles are not carried by the flow to thenext higher tray and they do not settle through the passages 152 to thenext lower tray.

Withrespect to tray 144 it should be noted that the horizontal portionof passage 152 is preferred to extend a horizontal distance of at leasttwice the height of the horizontal part of the passage. This horizontalportion of the passages 152 prevents the unloading of the column whenthe fluid upow stops.

The transport of the solids is accomplished by a short duration reversal(or pulse) of the uid upow through the column. As previously explained,the flow may be stopped momentarily before the reverse pulse to allowthe solid particles to settle into the bowls 150` and the passages 152.The reverse flow conducts the solid particles through the passages 152Where they are discharged horizontally below the tray into thecompartment next below, producing a generally circular flow patterntherein. The generally circular horizontal ow pattern so generateddelays the downward progress of the particles through the upper part ofthe compartment to minimize the number of such particles which arecarried through two trays during one reverse pulse. In use of tray 144,there is a tendency for the particles nearest the central axis of eachbowl 150 to be moved downwardly on flow reversal in preference to theparticles near the edge of each bowl.

As can be seen from the drawings, the bowls 150 are square at theirupper edges and have a circular crosssectional shape in their lowerportion. It is desired to have the bowls 150 of the largest dimensionpossible for economic considerations. However, contacting efficiency maybe reduced with an incresae in bowl size beyond a certain dimension.This reduction in contacting efliciency is believed to be caused by anaccumulation of particles part way between the cup perimeter and the oorof the bowl, which particles remain substantially stationary during theupow of fluid.

The preferred form of type A column contacting apparatus, as shown inFIGS. 7E and 7F, allows the use of a large size bowl without any loss ofcontacting eiciency. The cup 154 shown in FIG. 7E may be used as a trayor a plurality of such cups may `be formed into a single tray. The cup154 denes the upwardly facing bowl 156 which may be circular or squareat its upper edge. The upper edge of cup 154 is preferred to have anupper square configuration when several of the cups are to be combinedto form a single tray. In such tray, the ridges separating theindividual bowls are preferred to have a fairly sharp upper edge so thatparticles do not rest on the upper edges of the dividing ridges.

The cup 154 defines the port 158 communicating from the central portionof bowl 156 into the circular chamber 160. Passage 162 extends throughthe lower part of cup 154 tangentially into chamber 160. The conicaldeector 164 supported on rod 166 is psitioned within bowl 156concentrically above port 158 a distance approximately the diameter ofport 158. Conical deector 164 allows the the diameter of bowl 156 to beincreased appreciably while maintaining the solid particles duringcontact in a gentle continuous circulation. Additionally, the tangentialconnection of passage 162 into chamber 160 causes the uid flowingupwardly into the bowl to have a gentle rotational ow. This rotationalflow further assures the even distribution of upowing uid in the bowland the desired uidizing of the solid particles.

The movement of solid particles to the next lower tray during a reverseow pulse in cup 154 is improved as compared to tray 146. Thisimprovement results from deliector 164 directing the downflow outwardlybefore it reaches the port 158 to sweep the solid particles within thebowl 156 through the port 158, the chamber 160, and passage 162 into thecompartment below cup 154. Passage 162 discharges solid particleshorizontally into the compartment above the next lower tray to provide ameasure of assurance that the solid particles do not bypass a trayduring the reverse flow pulse. When fluid upow is discontinued, a columnof contacting apparatus according to the design of cup 154 does notunload solid particles. The particles are supported on each cup in thechamber 160 and in the passage 162.

FIGS. 8A, 8B, and 8C illustrate the action of the solid particles withinthe cup 154. In FIGURE 8A, the particles are shown to be distributedsubstantially uniformly in a uidized state within the bowl 156 atsubstantially the maximum rate of uid upflow through the cup. FIG. 8Brepresents a reduced fluid upflow rate and shows the settling of a fewsolid particles into the port 158 and chamber 160 with the majority ofthe particles being in iluidized contact within bowl 156. The staticcondition of no fluid ow is shown in FIG. 8C to illustrate the manner bywhich the solid particles are retained on the tray by the cup 154structure.

The contacting apparatus illustrated in FIGS. 9A, 9B, and 9C shows oneform of contacting structure 168 in which four of the preferred forms ofcontacting cups such as is shown in FIGS. 7E, 7F, 8A, 8B, and `8C arecombined into a square tray unit. Combinations such as 4, 9, 16, 25, 48or 100 such square units may be assembled to form a single contactingtray. Also, tray units may be comprised of seven hexagonally shapedcups.

The contacting structure 168 includes the bowl member 170 which definesthe four contacting bowls 172, the ring 174, and the annular deector176. Bowl member 170 is supported on plate 178. A conical defiector 180is supported above the central portion of each of the bowls 172 on legs182 and is secured in such position by screw 184. Screw 184 also clampsthe passage member 1'86 to the underside of plate 178. The box structure188 surrounds the contacting structure 168 and is positioned betweenplates 178 of adjacent trays. The height of box structure 188 determinesthe spacing between the trays 168 in the column. Where multiple trayunits are to be used the box structure would surround the complete traystructure. Ring 174 and deector 176 are suitably secured to plate 178 bysuitable means, such as, screws (not shown) extending therethrough andthreaded into plate 178.

Passage member 186 defines a chamber 190 positioned under and incommunication with the port 192 extending through bowl member 170 to thebottom of each bowl 172. Passages 194 are dened extending tangentiallyinto each chamber and opening to the underside of tray 168. As bestshown in FIG. 9C, the passages 194 are each directed tangentially withrespect to the interior of ring 174. Annular deector 176 extendsinwardly below ring 174 to dene the central opening 196 with uppersurface of deector 176 sloping inwardly and downwardly toward saidopening 196.

The operation of tray 168 is substantially the same as the operation ofcup 154 previously described except for the addition of ring 174 anannular deector 176 below each group of four cups. The primary functionof ring 174 and deilector 176 is to provide a delay in the downwardmovement of the solid particles with each ow reversal pulse. Deector176, by delaying the downward movement of the solid particles, allows alarger volume of uid to be pulsed to assure that all particles are movedto the next lower tray during each flow reversal pulse. The solidparticles travel from the bowls 172 through the ports 192, the chambers190 and are discharged through the passages 194 onto the interior ofring 174. During the ow reversal, most of the solid particles remainabove the central opening 196 because of the centrifugal action createdby the direction in which the passages 194 discharge the uid andparticles. When the pulse stops, the solid particles settle through thecentral opening 196 onto the next lower tray. The upper sloping surfaceof deflector 176 has a steep enough slope to assure that the solidparticles settle through opening 196.

that the material of the components is inert and does not contaminatesuch uids and solids.

The contacting structures shown in FIGS. 7A, 7C, 9A, and 9C use squareoutside configurations in order that a plurality of such modules mayconveniently be assembled laterally into a contacting structure ofpredetermined horizontal area. It is within the scope of this inventionto employ other outside geometric forms, including but not limited tohexagonal, circular and rectangular. Although the components shown inthe drawings may readily be made of plastic as previously discussed, itis in the scope of this invention that the components may be constructedof any suitable material. This applies particularly for applications atelevated temperatures.

As may be seen, the contacting structures for the type A column are sodesigned to allow a uidized contact between a fluid and solid particleswith the fluid maintaining the solid particles in an expanded or uidizedstate without carrying any appreciable number of solid particles betweenstages. Also, such structures allow the solid particles to betransported one stage at a time by a reverse pulse of the flowing fluidwhereby substantially all of the solid particles are 4transported onlyone stage with each reverse pulse. The delay means provided with thetray structures functions to prevent the movement of the solid particlesduring transport onto the next lower tray for a limited period of timeto assure that the solid particles do not bypass a tray structure duringtransport.

The preferred form of tray structure further provides a means ofpreventing the unloading of the column when no tluid is flowing and alsoprovides a means of causing the fluid to have a rotational ilow as itenters the contacting zone to assure uniform distribution of the liuidwithin the contacting zone.

The type A contacting structures are designed to be -made in multiplesto form a contacting tr-ay and the contacting trays are readilyassembled into a column in which the contacting and solid particletransport may be performed in accordance with the process of the presentinvention as herein described.

CONTACTING STRUCTURE lFOR TYPE B COLUMN FIGS. 10A and 10B show thecolumn 200 utilizing a plurality of cups 202 similar to cups 46previously discussed, to illustrate how the cups 46 may be used asmodules to form a -column including a plurality of ltrays each of whichincludes a plurality of the cups 46. Each of the trays 200 shown inFIGS. 10A and 10B are identical except that the intermediate 'tray ofthe trays shown is rotated 180 degrees in a horizontal plane withrespect to the other two trays shown. Each of the trays 200 is formed sothat the ridges 204 divide its upper surface into four bowls 206. Thetubes 208 which define the passage 210 may be formed integrally with thetray 200. Tubes 208 extend upwardly to a level slightly below the upperedge of walls 212 which extend upwardly around the outer edge of thetray and extend downwardly to terminate immediately above the next lowerbowl 206. The tubes 208 are offset to one side of the bowl 206 so thateach bowl has a tube 208 extending upwardly therein at one side andanother tube 208 extending downwardly therein from the next higher trayat the opposite side of the bowl.

When several of the trays 200 are assembled into a column, the rib 214on the lower side of each tray tits into the grove 216 formed in theupper edge of the walls 212. The trays 200 are also formed so that whenassembled two adjacent trays cooperate to eliminate sharp corners at theintersection of walls 212 with the underside of the next higher tray andalso around the tubes 2.08 at the point of intersection with theunderside of the tray through which they extend. The purpose of thisrounding of corners at the top of the compartment above 18 each tray isto effect the purging of air or gas completely through and out of thesystem by the downowing uid movement, which air otherwise tends toremain trapped in the upper portion of the compartment. The presence oftrapped air or gas in the column interferes with the proper movement ofsolids in this liquid system, since the air, because of itscompressibility, results in a dampening of the flow reversal pulse.

The operation of the column shown in FIGS. 10A and 10B is substantiallythe same as the operation of the column 44 shown in FIGS. 4A and 4B. Thenet fluid ow through the column of trays 200 is downwardly while thesolid particles are periodically moved upwardly in the column by areverse ow pulse. The solid particles are continuously contacted byfluid throughout the type B column. The solid particles are fluidizedwithin the bowls 206 below the level of the top of tubes 208 by the iiowof liuid downwardly out of passages 210 with the fluid continuingupwardly in bowls 206 and into the passages 210 at the top of the tubes208. The sol-id particles settle in the bowls 206 prior to theoccurrence of the reverse ow which causes the solid particles to becarried from the bowls 206 upwardly through the passages 210 to bedischarged from the top of tubes 208 and settle into the bowls 206 ofthe next higher tray 200 before the downward ow of the uid is restarted.The amount of uid moved during the reverse ow is preferably suflicientonly to move the volume of solid particles that have settled in each ofthe bowls 206 to the next higher tray 200. Allowing the solid particlesto settle prior to the occurrence of the reverse flow minimizes theamount of fluid moved during the reverse ow and avoids carrying of solidparticles past the next higher tray.

The contacting structures of the present invention for the type B columnare suitable to be made into trays and a plurality of trays connected toform a column. These structures provide intimate contact between the uidand the solid particles on each tray and allow the solid particles to betransported through the column one tray at a time responsive to areverse flow pulse of the uid and such transport is in a directionopposite to the normal settling direction of the solid particles in thefluid. For example, solid particles which normally settle downwardly aretransported upwardly through the type B column one tray or stage at atime with each reverse uid pulse.

The duid-solid contact on the type B tray structures provides anintimate contact with the solid particles being uidized by the uid flowwhile the possibility of carrying solid particles back to the next stagewith the Yiiuid is minimized.

CHEMICAL SEPARATIONS--URANIUM RECOVERY The application of the process ofthe present invention as it could be applied to a hydrometallurgicalprocess for the recovery of uranium is illustrated in FIGS. 11A, 11B,and 11C and is an example of chemical separation. After the uranium oreis ground, the uranium ions put into solution by means of an acid orother suitable treatment, and the large particles removed, the resultingslurry is fed to the type A exhaustion column 220 through inlet 322 atthe bottom of contacting section 221. As shown in FIG. 11C, the slurrypasses upward through the contacting section where it is stripped ofuranium ions by ion exchange resins to leave the column through outlet224 as a spent slurry. The ion exchange resins enter contacting section221 near the top thereof, and are moved downward by control means 223 incountercurrent contact with the upflowing slurry to remove the uraniumions from the slurry. After the resins pass through section 221, theycollect in reservoir 225. The resins are removed from reservoir 225 byresin control means 229 which controls the movement of the resins downthroigh washing section 227. In section 227 the resins are incountercurrent contact with pure water injected into the bottom of thissection by metering pump 226 yto rwash ythe yslurry from the resins.yThe slurry-ladenfwash vwater continuesy up through reservoir 225'to mixwithfthe enriched slurry in ysection v221.r f

The cross-sectional area; ofy rwash section y227 can be yay ffractionfof'the'cross-sectionalarea of rContact section 221 becausey theresin rparticles can be transferred through section 22""veryr rapidly.The small area of sectiony 227 minimizes wash water required and theresultant dilution of incoming slurry. Reservoir 231 collects theresinswhich f y f have passed through ysection 227. The resins areremoved f from reservoirf231 ybyfresin transfer means 230 and are fdelivered tothe type B column 228i. Resinftransfer rmeans f f 230'causesthefresins toy move upwardly through column v228, passing rstithroughregeneration section 233, rwhere f they are yin countercurrent'contactwithr the' regeneration solution injected into the column by meteringpump 232.

' v The; yuranium-rich regeneration or stripping ysolution yis f removedfrom the column'by metering 'pumpi236i and desy f v i livered toy vessel231'which represents facilities for ref tion yis, illustrative andexplanatory thereof, and yvariousv changes in the method, as well'asyin' the' details ofthe'y .illustrated construction, maybe made ywithinythey scope yof the appended yclaims without departing fromt theispirit.

yofthe,invention.y

by rrecovered and removed from ythe column vlay/.metering f fpumpf236The resins are delivered from the ytop'of column 22S into column220 accompanied by ya small amount of the pure wash water.

f Thus', the present yinvention. may be' used 'toy provide intimatecountercurrent contact between a uranium'slurry f and solid yresinparticles which particles-function. in ion v f exchange to; carry theuranium ions'outl ofy they uranium f slurry. vThe solid resin vparticlesmay theny be regenerated f to recover the uranium and yto vprepare thesolid resin particles yfor yreintroductiou into the exhaustion column.

RESUME y f f rFrom the foregoing it may be seen that thefpresentinvention provides an improved process for intimate countercurrentcontact between solid particles and a fluid such as water or a slurrycontaining uranium ions in solution. The process provides for thecirculation of the solid particles in a closed loop with the solidparticles being transported one stage at a time by a reversal of theflow in the vessel concerned. The process and apparatus thereforprovides a maximum of fluidized movement of the solid particles toassure that all solid particles are available for contact with the fluidin each stage without causing a transport of the solid particles betweenstages except when desired. Further, the transport of the solidparticles through their closed loop is such that in one portion thereofthey are moved in a direction opposite to their normal settlingdirection,

Both type A and type B columns of the present invention provide aplurality of stages of contact. In each stage the solid particles anduid are controlled to minimize channeling and to assure that relativelythe same amount of solid particles are maintained in each stage. Withthis control of the solid particles and the fluid ow, a type A column ofthe present invention may have thirty to forty stages in a column heightof sixteen feet. This allows the use of short vertical columns whichbecause of the particular tray structures of the present invention arenot limited in a lateral direction even with large fluid flow volumes.

Even though many of the solid particles used in uidsolid contactingprocesses are fragile, the present invention provides structure fortransporting the solid particles in the columns and for transferring thesolid particles between columns which minimizes the problems due tosolid particle attrition. The resilient valving members in the particletransfer means not only protect against particle damage but assure aseal against a valve seat even though solid particles may be trappedtherebetween.. The yparticle f ytransferrneansy ymay further be utilizedto control they f yvolume, of fluid transferred with the solidparticles.r f f f Thespeciic tray structures of the presentiinventonlare f y f designed ,toy ydistribute the uid flow uniformlythrough f ythefsolid particles and to assure that few, if yany',fof theyrsolid .particles remain on the tray yunexpiosed yto the fluid y tlow.yFurther,r certainof ythese tray structures are alsoy ,designed toyprevent unloading of the column when ttuidy f ow therethrough is shutoff'.

, The present invention thus provides a counter-current, multiple stage,duid-solid contacting process yhavingy 'a'y i greatly' improvedcontacting eciencyfand eliminating the f f rneed, toroutside ydevices,to transport the solid particles inl adirection opposite to theirnormal 'settling di're'ction'iny ,theud f Thus, ythis ,inventionyprovides methody and apparatus f yespecially suited to performingchemical' yselinarationsr f f f either by contacting ion exchange vresinf particles ywith f yzurionizecwl Huid, ,ory by contacting molecularsieve particles 1 ,with ay mixture ,of several liquids not necessarilyyionized', f f f The foregoing. disclosureandy description'offthevinvenn-Whatisclaimedis:l f. 1, 'Ihe methody of providing intimatecontactbetween ysolid particles and uids comprising,

l countercurrently ycontacting ythe f solid yparticles with ay yhuid ina plurality of stages in a first column,v

vsaidsolidy particles being tluidized in reachiof said stages, f

v by the ow ofy fluid through said rst column without ytransport of anappreciable amount of solid particles f between stages,

on each stage to the next stage in said first column in a 'directionyopposite toy they normal direction of fluid ow therein, delivering solidparticles from said first column to a second column, countercurrentlycontacting the solid particles with a fluid in a plurality of stages insaid second column, said solid particles being tluidized in each of saidstages by the tlow of uid through said second column without transportof an appreciable amount of solid particles between stages,intermittently reversing tluid ow in said second column to transport atleast a portion of the solid particles in each stage to the next stagein said second column in a direction opposite to the normal direction ofuid ow therein, and delivering solid particles from said second columnto said first column, the direction of transport of solid particles inone of said columns being opposite to the settling direction of thesolid particles in the fluid. 2. The method according to claim 1 whereinthe iluids contacting the solid particles are liquids. 3. The methodaccording to claim 2, including the steps of washing the solid particlessubsequent to at least one of said contacting steps and prior to thedelivering of the solid particles to the next contacting step. 4. Themethod according to claim 2, including the steps of washing the solidparticles with a liquid subsequent to both of said contacting steps andprior to the delivering of the solid particles to the next contactingstep. 5. The method according to claim 2, including the steps ofcontrolling the liquid flow rate in one of said columns t0 regeneratesolid particles suiciently to provide 21 the desired functions of thesolid particles with respect to the liquid in the other of said columns.6. The method according to claim 2, including the step of controllingthe reverse liquid flow in each column to .transport substantially allof the Solid particles only one stage with each intermittent liquid flowreversal. 7. The method according to claim 2, wherein the liquid ilow inone of seid columns is effectively stopped for a short period of timeimmediately preceding the reversing of fluid flow in said one columnwhereby the solid particles settleinto a position for transport prior totheir transport by the reversing of liquid flow. 8. The method oftreating a fluid comprising intimately contacting the fluid stream withsolid particles in a plurality of stages in a first contacting zonewherein the solid particles are fluidized by the fluid flow withouttransport of an appreciable amount of the solid particles betweenstages, regenerating solid particles by intimate contact with aregenerating fluid in a plurality of stages in a second contacting zonewherein said solid particles are fluidized by the flow of regeneratingfluid without transport of an appreciable amount of the solid particlesbetween stages, and circulating said solid particles in a closed loopthrough said first and second contacting zones responsive tointermittent reverse flow of said fluids in said zones to transport atleast a portion of solid particles on each stage to the next stage witheach flow reversal. 9. The method according to claim 8 including thestep of,

washing said solid particles after contact with said regenerating fluidto minimize the amount of said regenerating fluid carried by said solidparticles into said first contacting zone. 10. The method according toclaim 8 including the step of,

washing said solid particles after contact with said fluid stream tominimize the amount of said fluid stream carried by said solid particlesinto said second contacting zone. 11. The method according to claim 8including the step of,

intermittently reversing the llow of iluid in said contacting zones totransport the said particles therethrough one stage at a time. 12. Themethod according to claim 8 wherein, contacting fluid flow in one ofsaid columns is downwardly and the transport of solid particles isupwardly therein, and contacting fluid flow in the other of said columnsis upwardly and the transport of solid particles is dqwnwardly therein.13. The method according to claim 12 wherein, the direction of transportof solid particles in one of said columns is opposite to the settlingdirection of the solid particles in the fluid in said column. 14. Themethod of treating a liquid to remove components therefrom, comprisingintimately and countercurrently contacting the liquid with ion exchangeresin particles in a plurality of stages within a first contactingcolumn whereby the components to be removed are picked up in ionexchange by said resin particles, intermittently transportingsubstantially all of the resin particles in each of said stages in saidfirst column to the next subsequent stage responsive to reverse flow ofliquid in said first contacting column, transferring resin particlesfrom the last stages of said first column to the first stage in a secondcontacting column, intimately and ountercurrently contacting said resinparticles in a plurality of stages within said second column with aparticle regenerating liquid, washing said resin particles subsequent totheir contact with said regenerating liquid, intermittently transportingsubstantially all of the resin particles in each of said stages in saidsecond column to the next subsequent stage responsive to reverse flow ofliquid in said second contacting column, and transferring Washed andregenerated resin particles from the last stage of said second column tothe first stage of said first contacting column whereby said resins arecirculated in a closed loop through said contacting columns. 15. Themethod of treating a liquid according to claim 14, wherein delivering aportion of the contacted liquid from said first contacting column tosaid second column for the washing of said resin particles. 16. Themethod according to claim 15, wherein said regenerating liquid issupplied to said second contacting column in concentrations higher thanare desired in said second `contacting column and including the step of,

conducting liquid from said washing step to said second contacting stepto dilute said regenerating liquid to the desired concentration forregenerating said resin particles in said second contacting column. 17.The method according to claim 14 wherein the reverse liquid flow in oneof said columns transports said resin particles in a direction oppositeto their settling direction in the liquid within said column. 18. Themethod according to claim 14 wherein said liquid to be treated containsuranium ions in solution and including the step of treating saidregenerating liquid to recover a uranium product therefrom. 19. Anapparatus for treating a fluid by intimate contact with solid particles,comprising a first contacting column defining a plurality of contactingstages and having a fluid inlet, a fluid outlet, a solid particle inletand a solid particle outlet, a second contacting column defining aplurality of contacting stages and having a fluid inlet, a fluid outlet,a solid particle inlet and a solid particle outlet, means for deliveringsolid particles from the solid particle outlets of each of said columnsto the solid particle inlets of the other of said columns, means in saidcontacting columns for reversing the fluid flow in said columns totransport the solid particles one stage at a time between stages, saidparticle transport in one of said columns being in a direction oppositethe settling direction of the solid particles in the fluid within saidcolumn, means for independently and intermittently reversing the fluidflow a preselected amount in each of said columns, means for deliveringa solid particle regenerating fluid to the fluid inlet of said secondcolumn, and means for delivering fluid to be treated to the fluid inletof said first column. 20. The method of softening water, comprisingflowing hard water into a first contacting column having a plurality ofstages therein with each stage loaded with ion-exchange resins, saidwater intimately contacting said ion-exchange resins in each of saidcontacting stages 'whereby said water is softened, discharging softwater from the upper portion of said first column, intermittently movingresins through said column downwardly, transporting resins from thelower portion of said first column to the lower portion of a secondcontacting column,

flowing brine into an intermediate portion of said second contactingcolumn downwardly through a plurality of contacting stages to regeneratesaid resins,

flowing washing water into the upper portion of said second contactingcolumn downwardly through a plurality of contacting stages to wash thebrine from said resins,

discharging used brine from the lower end of said second column,

said resins in each of said stages being uidized by the brine and washwater owing downwardly in said column,

intermittently reversing the direction of ow in said second column tothereby simultaneously transport resins upwardly through said secondcolumn in the plurality of stages, and

transporting resins from the upper portion of said second column to theupper portion of said rst column.

21. The method according to claim 20, wherein the amount of the liquiddischarged from the bottom of said second column is su'iciently largerthan the amount of brine owing into said second column to provide thedesired amount of ow of soft water into and through said second column.

22. The method according to claim 20, wherein the concentration of thebrine flowing into the second column is greater than desired forregeneration of said resin particles to compensate for the dilution ofthe brine resulting from the flow of soft water into and through theupper end of said second column.

23. The method of softening water, comprising owing hard water into acontacting column near the lower end thereof and upwardly through aplurality of contacting stages,

discharging soft water from said column at a position above the upper ofsaid contacting stages,

charging each of said stages with a suitable quantity of ion-exchangeresins,

charging the uppermost stage with sufficient resins to provide an upperreservoir for such resins which have had their capacity to capturehardness ions properly regenerated before entering the reservoir,

said resins in each of said stages being fluidized by the water owingupwardly therethrough,

intermittently reversing the direction of water flow in said column tothereby simultaneously transport resins downwardly in the plurality ofstages including a quantity of resins from the upper resin reservoir anda like quantity of resins into a lower reservoir below the lowermoststage,

said ow reversal being controlled to transport a preselected quantity ofresins downwardly from each stage to the stage next below,

transporting resins from the lower resin reservoir to a regenerationcolumn,

regenerating the resins in said regeneration column with a regenerationagent,

washing the resins free of regeneration agent, and

transporting the resins from the regeneration column into the upperresin reservoir,

said resins being transported, regenerated and washed at a controlledrate to maintain a sufficient charge of resins in said first column tosoften the hard water owing into said rst column.

References Cited UNITED STATES PATENTS 2,632,720 3/1953 Perry 134-252,671,714 3/1954 McIlhenny et al. 210--33X 2,963,431 12/1960 Dorn et al1210-33 3,193,498 7/1965 Platzer et al. 2l0-38X 3,200,067 8/1965Levendusky 210-33X SAMIH N. ZAHARNA, Primary Examiner U.S. Cl. X.R.

ZIO-189, 195

